1. Field of the Invention
The present invention relates generally to a coaxial circulator and an element sharing device, and more particularly, to a coaxial circulator constructed so that a ferrite member to which a static magnetic field is applied is positioned at a junction of a Y-shaped strip conductor and an element sharing device using such a circulator.
2. Description of the Related Art
Conventionally, an element sharing device used in a wave decoupling device of a multiplex radio communications apparatus, such as an antenna sharing device, is formed from a waveguide component. In recent years, however, as devices have become cheaper and more compact, there is a growing need to make the element sharing device a coaxial component.
However, in an element sharing device, in which multiple. transmission frequencies pass through the same point, it is known that harmonic distortion (2f2xe2x88x92f1, f1+f2xe2x88x92f3) arises due to arbitrary two waves or three waves of the transmission frequency, and that, if this harmonic distortion enters the reception frequency band, the true reception signal is degraded. Normally, an isolation function of the circulator used on the element sharing device drops the harmonic distortion arising on the transmitting side to a level below which reception is no longer affected. However, harmonic distortion generated inside the element sharing device is transmitted as is to the reception side, creating many problems. Accordingly, it is desirable that no harmonic distortion be generated inside the element sharing device.
FIGS. 16, 17A, 17B, 18, 19A and 19B are diagrams illustrating the conventional art. FIG. 16 is a diagram showing an expanded view of a conventional coaxial circulator. As shown in the diagram, coaxial connectors 311 through 313 are mounted at three openings in the sides of a metal block 11 and a Y-shaped inner conductor 13 (having a circular junction at a center thereof) is fixedly mounted by soldering between the three central conductors 311 through 313. On a top side of the inner conductor 13 are mounted, in order, a polytetrafluoroethylene support 15a and a ferrite member 17a whose position is determined by the polytetrafluoroethylene support 15a, a copper disc 19a, an aluminum ring 21a and a magnet 23a whose position is determined by the aluminum ring 21a, on top of which a yoke 25a is mounted and attached to the block 11 by using a screw. The bottom side of the inner conductor 13 is configured similarly.
FIGS. 17A and 17B are second diagrams illustrating the conventional art. FIG. 17A is a plan view of the inner conductor 13 and FIG. 17B is a cross-sectional view of an assembled coaxial circulator along the line axe2x80x94a of FIG. 17A.
It should be noted that, in order to prevent the occurrence of harmonic distortion in a coaxial circulator of this type, the copper discs 19a, 19b that contact the ferrite members 17a, 17b must be securely electrically grounded.
FIG. 18 is a third diagram illustrating the conventional art, and more specifically, shows an expanded view of an upper right portion of FIG. 17B. Conventionally, ring 21a is thickened, so that when a screw 35 is tightened to a screw hole 33 in the block 11, the yoke 25a urges the ring 21a downward, pressing the copper disc 19a against an inner stepped portion of the block 11 so that the copper disc 19a is grounded. The copper disc 19b is similarly grounded.
However, the problem with the above-described arrangement is that the seating of the copper discs 19a and 19b against the block 11 becomes partially inadequate if the parts on the inside of the copper discs 19a, 19b, (that is, the ferrite members 17a, 17b, the polytetrafluoroethylene supports 15a, 15b, and so on) are not shaped exactly to the correct dimensions, and this inadequate or incomplete contact generates harmonic distortion.
FIGS. 19A and 19B are fourth diagrams illustrating the conventional art. FIG. 19A, for example is a diagram showing output characteristics in the event that harmonic distortion (two-wave and three-wave distortion) is generated.
It should be noted that it has been confirmed that the state of the grounding of the copper discs 19a and 19b to the stepped portion of the block 11 can be improved by inserting copper foil thereinbetween, thus making it possible to improve the output characteristics. FIG. 19b shows such improved output characteristic.
However, insertion of the copper foil is an unsatisfactory solution to the above-described drawback because it complicates the structure of the device.
Accordingly, it is a general object of the present invention to provide an improved and useful coaxial circulator and element sharing device in which the above-described disadvantages are eliminated.
Another and further object of the present invention is to provide an improved and useful coaxial circulator and element sharing device having a simple structure that adequately suppresses harmonic distortion.
The above-described objects of the present invention are achieved by a coaxial circulator having ferrite members to which a static magnetic field is applied disposed at a junction of a Y-shaped strip conductor, the coaxial conductor comprising:
a dielectric substrate;
an inner pattern of the Y-shaped strip conductor provided on a center of an upper surface of the dielectric substrate; and
ground patterns provided on the upper surface and a lower surface of the dielectric substrate along a periphery of the conductive inner pattern and electrically connected to each other via a plurality of through-holes in the dielectric substrate,
the substrate being sandwiched by an upper block and a lower block, the ferrite members being provided adjacent to both the upper side and a lower side of the substrate so as to ground the ground patterns to the upper and lower block surfaces.
According to the invention described above, by providing a,conductive inner pattern on top of the dielectric substrate, together with the peripheral ground patterns a variety of waveguide structures (that is, characteristics) can be achieved. Additionally, changes to the conductive inner pattern can be easily added, thus making it possible to provide a coaxial circulator with the desired characteristics without regard for variations in the characteristics of peripheral components. Additionally, the ground patterns of the dielectric substrate are sandwiched by the ground faces of the blocks together with the upper and lower ferrite members the bringing together of which makes it possible to obtain a full and complete ground plane of the waveguides (specifically, the upper and lower edge surfaces of the ferrite members on the periphery of the conductive inner pattern.
The above-described objects of the present invention are also achieved by device comprising:
a single dielectric substrate having dielectric substrate portions of a plurality of coaxial circulators, a Y-shaped conductive inner pattern provided on a center of an upper surface of each one of the dielectric substrate portions, ground patterns provided on the upper surface and a lower surface of each of the dielectric substrate portions and electrically connected to each other via a plurality of through-holes formed in each of the dielectric substrate portions along a periphery of the conductive inner pattern, each of the dielectric substrate portions being sandwiched by an upper block and a lower block, ferrite members being provided adjacent to both the upper side and the lower side of each of the dielectric substrate portions so as to ground the ground patterns to the surfaces of the upper and lower block; and
the plurality of coaxial circulators directly coupled to each other via the single dielectric substrate.
According to the invention described above, by directly coupling a plurality of coaxial circulators via a single dielectric substrate structure, the harmonic distortion generated at the conventional connecting portions can be adequately suppressed.
The above-described objects of the present invention are also achieved by a coaxial circulator having ferrite members to which a static magnetic field is applied disposed at a junction of a Y-shaped strip conductor, the coaxial circulator comprising:
an intermediate block containing a central conductor and the ferrite members provided at top and bottom sides of the central conductor; and
an upper block and a lower block, surfaces of the upper block and the lower block contacting upper and lower surfaces of the intermediate block, respectively.
The above-described objects of the present invention are also achieved by a coaxial circulator having ferrite members to which a static magnetic field is applied disposed at a junction of a Y-shaped strip conductor, the coaxial circulator comprising:
an upper block and a lower block;
a central conductor positioned between the upper block and lower block; and
a supporting member positioning the ferrite members within an interior space formed by the upper block and the lower block.
According to the invention described above, a secure ground plane can be obtained within the waveguide space of the circulator using a simple structure, so the internal generation of harmonic distortion can be adequately suppressed.
Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.